1. Field of the Invention
The present invention relates to a control system for fuel vapors released from a vehicle fuel tank and, more particularly, to a vent structure for admitting and exhausting air to and from a fuel canister connected to a vehicle fuel tank while preventing water, snow and the like from entering the same. The present invention finds particular application as a joint box for filter and drain tubes connected to a fuel canister and will be described with particular reference thereto. It is to be appreciated, however, that the invention may relate to other similar environments and applications.
2. Description of the Prior Art
It is known that a vehicle""s fuel tank often holds fuel vapor in addition to any amount of liquid fuel stored in the fuel tank. When the fuel tank is being filled with liquid fuel, an amount of the fuel vapor may be displaced from the fuel tank. Similarly, if the temperature of the vehicle fuel tank rises, an amount of the fuel vapor may be displaced. For environmental reasons, it is undesirable to release such displaced fuel vapor into the atmosphere.
To avoid the release of displaced fuel vapor to the atmosphere, the vehicle fuel tank is typically connected to a fuel canister for venting the fuel vapor thereto. The fuel canister is adapted to temporarily retain the displaced vapor thereby preventing the displaced fuel vapor from being released into the atmosphere. More particularly, the displaced fuel vapor enters the fuel canister from the fuel tank wherein the fuel vapor is absorbed in a carbon bed contained within the fuel canister. The absorption of displaced fuel vapor within the canister displaces air within the canister. This air is vented to atmosphere.
The retention of the displaced fuel vapor within the canister is only temporary. More particularly, the fuel vapor retained in the fuel canister must be purged to allow the canister to accommodate and absorb additional displaced fuel vapor from fuel tank that may occur at a later time. To purge the absorbed fuel vapor, atmospheric air or purge air is drawn into the canister and through the carbon bed. The purge air passes a dust separator prior to entering the canister which cleans or filters the purge air. After passing through the canister, the purge air is sent to the engine for utilization. After purging, an amount of atmospheric air occupies the fuel canister until another amount of displaced fuel vapor enters the canister and forces the air therein to exit the canister.
In many prior art vehicle fuel systems, a tube or like conduit is attached at a first end to the fuel canister. The second end of the tube is secured to or within a body part or panel of the vehicle. The tube permits air to enter and exit the fuel canister as displaced fuel vapor exits and enters the fuel canister. The second end of the tube, secured to a body part or panel, is oriented such that water, snow, debris and the like are prevented from or have difficulty entering the tube and, therethrough, the canister.
In some vehicles there is not a suitable body part or panel to which the second end of the tube may be attached and oriented to discourage the entrance of water, snow, debris and the like. A vehicle body part or panel may be unsuitable because its location on the vehicle makes attaching the tube thereto impractical or it may be a part that if the tube was attached thereto, air exiting the tube could enter the passenger cabin of the vehicle. Allowing air to exit the tube into the vehicle cabin is undesirable because there is no filter to ensure that some fuel vapor does not enter the cabin with the air.
Thus, there is a need for a fuel system having a vent structure that permits atmospheric air to enter and exit a fuel canister while preventing or at least obstructing water, snow, debris and the like from entering the fuel canister when the vehicle has no suitable component for attaching a second end of a tube that communicates with the fuel canister. The present invention provides a new and improved fuel system having a vent structure that overcomes the foregoing difficulties and others and provides the aforementioned advantageous features.
In accordance with one aspect of the present invention, a new and improved evaporative fuel system is provided. More particularly, in accordance with this aspect of the invention, the evaporative fuel system includes a canister connected to a fuel tank for receiving vapors therefrom and a conduit having a first end connected to the canister. A vent structure is connected to a second end of the conduit. The vent structure includes a housing first port formed in the housing and connected to the conduit, and a second port formed in the housing and connected to atmosphere. A chamber portion is formed by the housing and is in airflow communication with the second port. A tubular portion is formed by the housing and is in airflow communication with the first port and the chamber portion. The tubular portion extends into the chamber portion. A baffle is adjacent the second port and extends into the chamber. The baffle and the tubular portion together define a sinuous path portion of an air passageway extending between the first port and the second port.
According to another aspect of the present invention, a new and improved vent structure for an evaporative fuel canister is provided. More particularly, in accordance with this aspect of the invention, the vent structure includes a housing having a first end and a second end. A cavity is defined within the housing. A first ambient port is defined in the housing adjacent the second end and is connected to the cavity. A second ambient port is defined in the housing adjacent the second end and is connected to the cavity. The second ambient port is oriented below the first ambient port. A canister port is defined in the housing adjacent the first end and is connected to the cavity. The canister port is adapted to be connected to a port of an associated evaporative fuel canister. A fin is disposed in the cavity for directing fluid entering at least one of the first ambient port and the second ambient port to exit the cavity through at least one of the first ambient port and the second ambient port.
According to still another aspect of the present invention, a vent structure having an opening for allowing a connected fuel canister to vent airflow to atmosphere while preventing fluids from entering the canister through the opening is provided. More particularly, in accordance with this aspect of the invention, the vent structure includes a housing defining at least one air passageway therethrough. A first ambient port is defined in the housing connecting the at least one passageway to atmosphere. A second ambient port is defined in the housing connecting the at least one air passageway to atmosphere. A channel member defining a portion of the at least one air passageway is provided. The channel member has at least one canister port defined by the housing for connecting the at least one air passageway to the associated canister. A first baffle is adjacent the first ambient port. A second baffle is adjacent the second ambient port. The housing, the channel member and the first baffle together define a first air passageway of the at least one air passageway having a circuitous path between the first ambient port and the at least one canister port. The housing, the channel member and the second baffle together define a second air passageway of the at least one air passageway having a circuitous path between the second ambient port and the at least one canister port.
According to another aspect of the present invention, a new and improved canister vent is provided. More particularly, in accordance with this aspect of the invention, the canister vent includes a body having a first end and a second end. At least one canister port is defined by the body and located adjacent the first end. A cup portion is defined by the body. The cup portion has a base wall and at least one sidewall that together define a cup cavity adjacent the second end. A channel member extends into the cup cavity from the base wall. The channel member defines an opening spaced apart from the base wall. An air passageway fluidly connects the at least one canister port and the channel member opening. An end cap connects to the body for closing an open side of the cup cavity. The end cap includes at least one end cap port therethrough and at least one baffle extending into the cup cavity for obstructing direct flow between the at least one end cap port and the channel member opening.